The invention relates to a bone graft composition, method and implant for new tissue formation, including the surgical fixation of a joint to promote bone fusion. In an embodiment, the invention includes an absorbable matrix material in combination with an osteogenic composition.
A bone graft is a surgical procedure to place new bone into spaces around a broken bone or in between holes or defects in bone. The procedure can be used to repair broken bones that have bone loss, to repair injured bone that has not healed or to fuse joints to prevent movement. The bone graft procedure may be ancillary to an osteosynthesis, which is a surgical procedure that stabilizes and joins the ends of fractured bones by mechanical devices such as metal plates, pins, rods, wires or screws. The term “osteosynthesis” refers to internal fixation of a fracture by such means, as opposed to external fixation of a fracture by a splint or cast. Or, a bone graft may be part of a spinal fusion in which two or more of the vertebrae in the spine are united together so that motion no longer occurs between the vertebrae.
Modern bone grafting uses biologically active agents such as osteoinductive tissue growth factors to regenerate bone or cartilage. Bone morphogenetic proteins such as rhBMP-2, rhBMP-7 and rhBMP-12, are examples of osteoinductive tissue growth factors. Bone and articular cartilage regeneration with bone morphogenetic protein can be achieved through a tissue engineering approach based on bioresorbable synthetic osteoconductive scaffolds. These scaffolds are used to fabricate anatomically and functionally specific three dimensional tissue architecture. In some forms, the scaffolds provide a sponge matrix for the delivery of the biologically active agent and living cells to bone or cartilage defect.
Instructions for use of these materials suggest that compression of the biologically active agent within the osteoconductive media is undesirable. Compression or squeezing of the osteoconductive sponge matrix can result in migration of the beneficial biologically active therapeutic fluids away from treated anatomic structures. Also, compression, torsion or another force can cause the matrix to shift, extrude or rotate in placement.
There is a need for resorbable bone grafts with improved handling and compression resistance. There is a need for a bone graft implant that provides improved stability and mechanical strength and that resists shifting, extrusion and rotation after implantation.